1. Field of the Invention
The present invention relates to air-cooled internal combustion engines equipped with at least one hydronamic retarder and in particular to the combination of such an engine and a cooling system for the hydronamic retarder fluid.
2. Description of the Prior Art
Internal combustion engines equipped with hydronamic retarders are well-known and one such engine is described in West German Pat. No. 1,230,615, in which engine the retarder oil cooler is located on the coupling side of the internal combustion engine and in series with the cylinders. This cooler is closed by exhaust valves during the normal operation of the cooler; however, when the retarder is in operation, the exhaust valves are opened whereby the cooling air may flow in the desired direction through the retarder oil cooler. The opening of the exhaust valves, however, causes the pressure in the system to diminish such that a relatively small volume of air flows through the retarder oil cooler and hence, a relatively large cooler must be provided in order to dissipate the heat produced. Such large and bulky retarder oil coolers are difficult to mount in modern automobiles because of the cramped assembly of the latter.